Uneven lighting on one side after dropping

Hello everyone,

After dropping my iPad air 2 while it was inside the backpack, on the left side of the screen has uneven backlight, as you can see in the picture. All screen functions are normal, multi touch works well, color still accurate, no crack on screen. Apple service center told me to replace the whole screen, which would cost me a brand new iPad. I don’t think the lcd panel itself has any problem. What do you think about it? How should I repair it? Thank you very much!